Electric horn



Aug. 11, 1925. 1,549,132

E. A. GRAHAM ELECTRIC HORN Filed March 2, 1921 0 3 Sheets-Sheet l 35 36 4, 1 j, @11 I @10 I 14 A 1135K I 1 37 9- ya/ @11 19 20 11a :5 30 19 Aug. 11, 1925. 1,549,132

E. A. GRAHAM ELECTRIC HORN Filed March 2, 1921 a Sheets-Sheet 0 Aug. 11,. 1925..

1,549,132 E. A. GRAHAM ELECTRIC .HORN

Filed March 2. 1921 3 Sheets-Sheet 5 INVENTOR 6mm W rfimwml a" m Patented Aug. 11, i925.

ELECTRIC noun.

Application filed March 2, 1921. Serial NO- 449, 33.

T all whom it may concern:

Be it known that I, EDWARD ALFRED GRA- HAM, a subject of the King of Great Britain and Ireland, residing at Brockley, in the county of London, England, have invented Improvements in Electric Horns, of which the following is a specification.

This invention relates to electric hooters or sound producing devices of the vibrating plate or diaphragm type. A form of hooter of this type is known in which a vibrating member, influenced by an electro-magnet, is secured at one end, adapted at the other end to open and close the circuit of the electromagnet and connected by a jointed device to the diaphragm so that the member and diaphragm vibrate together. According to the present invention a similar arrangement is employed but inlieu of the electro-magnetically influenced member being connected to the diaphragm to vibrate together in unison, a loose coupling is employed comprising an anvil upon the diaphragm against which the member aforesaid is adapted to strike after it has moved to a certain extent independently thereof. Such a modification is adapted to produce a loud and clear musical note of a penetrating character with only a small expenditure of electric energy.

Ordinarily also, horns of the general type referred to, are so constituted that the diaphragm is in a plane perpendicular to the axis of the trumpet which plane is usually substantially vertical. In consequence there- 35 of there is frequently a tendency for dust and dirt to collect and water to accumulate in the region of and upon the diaphragm and associated parts which, by damping the vibration thereof, or deteriorating the ma- 41) terial, as by rust or corrosion, may impair the operation of the same. A. further object of the present invention is to overcome this disadvantage and it is achieved by arranging that the diaphragm shall occupy a 415 plane parallel or substantially parallel to the axis of the trumpet and arranged horizontally above such axis so that dust or dirt entering the trumpet does not tend to impinge directly upon the diaphragm but is arrested in a more or less abrupt region at the rear of the trumpet and below the diaphragm, into which region furthermore particles of dust that may reach the diaphragm can fall again by gravity, lnore particularly after they have been dislodged by the diaphragm vibration. liurther the whole apparatus is so mounted, by means of an adjustable supporting bracket, that it may be attached to any part of an automobile or the like the surface of which may be vertical, horizontal or oblique.

In the accompanying drawings, Figs. 1 and 2 show a sound producing device according to the invention, particularly suitable as a hooter or horn for use on road vehicles or for other purposes, Fig. 1 being a plan with parts removed and Fig. 2 a cen tral section on the line A B of Fig. 1. Figs. 3 and 4t are sections corresponding respectively to the lines C D and E F of Fig. 1. Fig. 5 is a side elevation. Fig. 6 an underside plan and Fig. 7 a rear end elevation of a horn embodying the device shown in Figs. 1 to a. Fig. 8 is a section on the line GH of Fig. 1.

As shown in Figs. 1 to 4, 7 is a base plate upon which is secured by screws 11 an iron arch-shaped yoke piece 11 in which are mounted two electromagnetic coils M having tubular iron cores with adjustable central pole pieces 1 1 screwed to the yoke piece and secured by locknuts 18.

Mounted on the base plate 7 is a spring strip 6 which bridges an elongated aperture 7 in the said plate. The spring strip car- 35 ries an armature 8 provided with a button 12 0f insulating material. The armature 8 is arranged diametrically of a diaphragm 41, which may be formed of alloy steel, such as vanadium steel, and passes through a stirrup-like or annular anvil-piece 10 which is located between the coils M and is riveted, or otherwise rigidly attached, to the said diaphragm. The base plate 7 also carries a resistance 36 which is connected in known way as a shunt across the windings of the electro-magnet coils M.

The insulated button 12 bears normally against aspring blade 19 carrying a contact 1?) which co-acts with a second contact 2O on a spring blade 20 in order to close a circuit through the said electroanagnet coils at this point.

A milled headed adjustment screw 30, having a locking spring 81, passes thiaugh a terminal piece 22, which is fixed to the base plate 7 by screws 32 but insulated therefrom and is electrically connected to the said spring blade 20, as by a. linking piece 29, (Fig. 1) the screw 30, by bearing upon said spring blade, allowing the position of the same to be adjusted. By these means thedegree of pressure between the contacts 19 and 20 can be easily varied. The terminalpiece 22 also carries a terminal screw 23,,and an insulated terminal bush 41 the terminal screw 23 of which constitutes a second main terminal connection for the apparatus.

A stud pillar 16, riveted or otherwise attached to the magnet yoke piece 11, passes through the domed cover 2 which is secured in place by the rounded nut 17 which encloses an oiled leather washer or the like for the exclusion of moisture and dust.

The diaphragm 4 is mounted between an elastic gasket or packing ring 5 and awasher 3 of paper, these, together with the diaphragm, being clamped between the base plate 7 and the cap piece 40 of the horn.

The action of the apparatus is as follows On closing a key or push, current passes from one pole of a battery or like source of supply to the terminal 23, thence through the electro-magnetic coils M in parallel with a resistance orra condenser, to the sprmg blade 19 and thence through contacts 19 and 20, spring blade 20 and link- 29 (Fig. 4) to terminal piece 22 and terminal screw 23 which is connected to the other pole of the battery through the key or push, in known manner. The electromagnetic circuit, comprising the armature '8, pole pieces 14 and yoke 11 being thus excitedfby; the current flowing, the armature 8 moves upward and strikes the inner face of the skeleton anvil lOrsharply, thereby setting the diaphragm 4 into vibration. During the latter portion of the motion of the armature 8, the button 12 moves contact 19 out of engagement with contact 20% The armature 8 is consequently released and, under the action of the springs 6 and 19 is moved to its original position, whereupon the circuit is again established, the same cycle of operation being repeatedly passed through and giving a sustained note so long as the key or push A is closed.

The pressure and duration of the contact at 19 and- 20 can, asjhereinbefore described, be varied by rotation of the screw 30, thereby allowing the character and tone of the emitted note to be varied as desired.

The pole pieces 14 are not necessarily adjustable and instead of two electro-magnetic coils M with pole pieces, a single coil with pole piece may in some cases be used.

'As shown in Figs. 5 and 6 the diaphragm 4 and domed cover 2 a1'e carried by acap pieco 40 formed in one with a chamber 41 to which the trumpet 42 may be attached in any convenient way, said member 41 having a substantial lug 43 adapted to be engaged at opposite sides by a pair of brackets 44 through which and the lug a bolt 45 'is passed. -In this way the angular relationship between the lug 43 and brackets 44 can be adjusted to enable the casing 41 with trumpet 42 to be carried in a horizontal position from supports to which the brackets require to be secured at varying angles. a

What I claim is 1. An electric horn comprising a base plate having an opening therethrough a yoke piece fixed to one side of said base plate, an electro-magnet carried by said yoke piece, a diaphragm at the opposite side of said base plate, a cap piece secured to said base plate and clamping the diaphragm in position, said cap piece having a central sound exit opening, a stirrupshaped anvil fixed to the central portion of said dia hra 'm and extending throu h the i: Q in cap piece secured to the peripheral portion of said base plate and having a centrally arranged sound exit branch, a diaphragm fined at its periphery between the base plate and cap piece, an electro-magnet comprising a yoke piece fixed to said base plate, a pillar extending upward from said yoke piece, a dome shaped cover secured to said pillar and extending around said base plate, a stirrup shaped anvil fixed to the central portion of said diaphragm and extending through the hole in said base plate, a spring supported armature located between said base plate and electro-magnet, extending freely through the said anvil and adapted to strike the end of the anvil remote from the diaphragm when attracted by said electro-magnet and a normally closed circuit making and breaking device for said. electromagnet independent of said armature and comprising insulated spring blades carried by said base plate and arranged to be moved apart by said armature when attracted by said electro-magnet.

Signed at St. Andrews Works, Crofton Park, Brockley, in the county of London, England, this fourteenth day of February, 1921.

nnwann ALFRED GRAHAM, 

